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How to demist your windscreen in double-quick time

17 Jan 2013 at 12:15

A severe cold snap is sweeping the nation at the minute, meaning many morning motorists could face icy windscreens and condensation on their way to work.

If you battle with scrapers, fight with rags and curse the heater in a bid to clear your windscreen as fast as possible, take note – here are our top tips on demisting your vehicle’s glass surfaces as quickly as possible:

If your car has air conditioning, make sure it’s switched on and the heater blast is directed at the windscreen. Misting is caused by water vapour condensing on the screen – the air-con will dry out the air, removing any moisture.

Use this in conjunction with the heater. Hot air will dry the glass a little through evaporation, but the air will then cool down and condense on the glass once more, so make sure the A/C is on to keep the atmosphere inside dry. If you’re windscreen is iced over, then the heat is obviously more necessary.

If you don’t have a clever climate control system, driving along with the windows down could actually help clear the screen faster. Although it might feel cold, the dry, rushing air from outside can help reduce the amount of water vapour inside the car, stopping the screen misting up.

If you DO have a clever climate control system, utilise it. There’ll most likely be a setting for demisting the windscreen, which will automatically adjust the ventilation system’s parameters to achieve the best results.

Your body actually has an effect on your windscreen fogging up. Have you ever noticed that when its cold but your screen isn’t misty as soon as you get inside your vehicle it starts to steam over? It’s the same as blowing on a piece of glass…

Your body heats the air inside the cabin – as does your breath – increasing the amount of moisture it can hold. This means when it comes into contact with your windscreen it cools and condenses, forming a mist.

Start the heater off cold, then slowly increase the temperature as the air dries out, rather than overloading the cabin with hot, ‘wet’ air. Try to find a temperature and humidity that’s comfortable but doesn’t mist up the cabin.

Of course, if your frozen bones need warmth more than you value a clear screen, we understand. Just don’t move off until all glass surfaces on your car are clear. It’s dangerous and also illegal if visibility is impeded.